CONSUMERS should consider "voting with their feet" if British Gas fulfils reports by putting up bills by 25%, an expert in the market said last night.

A Sunday newspaper said the company was set to announce their biggest single increase ever.

Tim Wolfenden, product strategy manager of switching and comparison service uSwitch.com said: "Consumers should consider, 'are we paying the best price?' and think about voting with their feet."

The newspaper said British Gas would announce the price hike this month in letters to its 11 million consumers.

Gas and electricity watchdog, energywatch, said that if there was such an increase, it would expect consumers to leave British Gas.

Adam Scorer, campaigns director of energywatch, said: "Should a major supplier, British Gas or anybody else, raise prices by 25%, we would expect consumers to respond angrily, by leaving for a better deal.

"Such a rise would be unprecedented since the start of competition."

A spokesman for Centrica, the parent company of British Gas, said: "Wholesale gas prices for 2006 are up about 75% on 2005.

"Clearly all suppliers are buying their gas in the same market, therefore we would expect that suppliers will be increasing their tariffs substantially as we go through 2006.